U.S. patent application number 11/357919 was filed with the patent office on 2006-08-03 for on demand morphable automotive body moldings and surfaces.
Invention is credited to Alan L. Browne, Nancy L. Johnson, Ivan G. Sears.
Application Number | 20060170243 11/357919 |
Document ID | / |
Family ID | 46323859 |
Filed Date | 2006-08-03 |
United States Patent
Application |
20060170243 |
Kind Code |
A1 |
Browne; Alan L. ; et
al. |
August 3, 2006 |
On demand morphable automotive body moldings and surfaces
Abstract
A morphable vehicle member utilizing at least one active
material to change at least one attribute in response to an
activation signal. The change in at least one attribute is a change
in a shape dimension, a shape orientation, an expansion, a
contraction, a morphing, a yield strength property, a flexural
modulus or a combination. Preferably, the change in at least one
attribute in the morphable vehicle member is reversible. Also
disclosed herein are methods for the morphable vehicle member
utilizing at least one active material to change at least one
attribute on demand in response to an activation signal.
Inventors: |
Browne; Alan L.; (Grosse
Pointe, MI) ; Johnson; Nancy L.; (Northville, MI)
; Sears; Ivan G.; (Rochester Hills, MI) |
Correspondence
Address: |
GENERAL MOTORS CORPORATION;LEGAL STAFF
MAIL CODE 482-C23-B21
P O BOX 300
DETROIT
MI
48265-3000
US
|
Family ID: |
46323859 |
Appl. No.: |
11/357919 |
Filed: |
February 17, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11075837 |
Mar 9, 2005 |
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11357919 |
Feb 17, 2006 |
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60654312 |
Feb 19, 2005 |
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60552677 |
Mar 12, 2004 |
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Current U.S.
Class: |
296/146.9 ;
180/89.1; 428/412 |
Current CPC
Class: |
B60R 13/04 20130101;
B60R 19/03 20130101; B60R 13/043 20130101; B29C 33/44 20130101;
B62D 39/00 20130101; B62D 35/00 20130101; Y10T 428/31507 20150401;
B60R 19/50 20130101; B29C 33/308 20130101 |
Class at
Publication: |
296/146.9 ;
180/089.1; 428/412 |
International
Class: |
B60J 10/08 20060101
B60J010/08 |
Claims
1. A morphable vehicle member, comprising: a non-active material
based portion coupled to an active material based portion, wherein
the active material based portion comprises an active material
adapted to change at least one attribute in response to an
activation signal, wherein the change in the at least one attribute
changes a modulus property, a shape orientation, or a combination
of the modulus property change and the shape orientation change to
the active material based portion; an activation device in
operative communication with the active material adapted to provide
the activation signal; and a controller in operative communication
with the activation device.
2. The morphable vehicle member of claim 1, wherein the at least
one active material comprises a shape memory polymer, a shape
memory alloy, a magnetic shape memory alloy, an electroactive
polymer, a magnetorheological elastomer, a magnetorheological
fluid, an electrorheological fluid, electrorheological elastomer,
an ionic polymer metal composite, a piezoelectric, or a combination
comprising at least one of the foregoing active materials.
3. The morphable vehicle member of claim 1, wherein the change in
the at least one attribute is reversible.
4. The morphable vehicle member of claim 1, wherein the vehicle
member spans across an interface of a doorframe surface and a door
surface.
5. The morphable vehicle member of claim 1, wherein the activation
signal is a selected one of a thermal signal, an electrical signal,
a magnetic signal, a mechanical signal, a chemical signal, and a
combination comprising at least one of the foregoing signals.
6. The morphable vehicle member of claim 1, wherein the active
material based portion comprising a flexible covering, a rigid
base, and the active material intermediate the flexible covering
and the base.
7. The morphable vehicle member of claim 1, wherein the vehicle
member is aligned with a contour of a surrounding surface in an
unpowered state and projects from the surrounding surface in a
powered state.
8. At least a two part morphable molding for a vehicle contiguously
spanning an interface of a door and a doorframe, the morphable
molding comprising: a first molding attached to the doorframe
surface; a second molding attached to the door comprising an active
material based portion contiguous to the first molding, the active
material based portion comprising an active material adapted to
change at least one attribute in response to an activation signal,
wherein the change in the at least one attribute changes a modulus
property, a shape orientation, or a combination of the modulus
property change and the shape orientation change to the active
material base portion to provide door clearance upon opening the
door an activation device in operative communication with the
active material adapted to provide the activation signal; and a
controller in operative communication with the activation
device.
9. The morphable vehicle member of claim 8, wherein the at least
one active material comprises a shape memory polymer, a shape
memory alloy, a magnetic shape memory alloy, an electroactive
polymer, a magnetorheological elastomer, a magnetorheological
fluid, an electrorheological fluid, electrorheological elastomer,
an ionic polymer metal composite, a piezoelectric, or a combination
comprising at least one of the foregoing active materials.
10. The morphable vehicle member of claim 8, wherein the change in
the at least one attribute is reversible.
11. The morphable vehicle member of claim 8, wherein the activation
signal is a selected one of a thermal signal, an electrical signal,
a magnetic signal, a mechanical signal, a chemical signal, and a
combination comprising at least one of the foregoing signals.
12. The morphable vehicle member of claim 8, wherein the active
material based portion comprising a flexible covering, a rigid
base, and the active material intermediate the flexible covering
and the base.
13. A method for selectively forming or erasing a raised pattern in
a vehicle surface, the method comprising: forming a pattern
comprising an active material in the vehicle surface, wherein the
active material has a selected one of a trained shape that projects
from a surrounding vehicle surface and a trained shape that is
substantially aligned with a contour of the surrounding surface;
activating the active material, wherein activating the active
material changes the selected one of the trained shape that
projects to the substantially align with the contour of the
surrounding surface and the trained shape that is substantially
aligned to project from the contour of the surrounding vehicle
surface; and deactivating the active material.
14. The method of claim 13, wherein activating the active material
is in the absence of a load.
15. The method of claim 13, wherein the active material is a shape
memory polymer, a shape memory alloy, a magnetic shape memory
alloy, an electroactive polymer, a magnetorheological elastomer, an
electrorheological elastomer, and combinations thereof.
16. The method of claim 13, wherein the pattern that projects from
the contour of the surrounding surface projects inwardly.
17. The method of claim 13, wherein the pattern that projects from
the contour of the surrounding surface projects outwardly.
18. The method of claim 13, wherein the vehicle surface is at least
one of a vehicle bumper, an interior surface, a steering wheel
surface, a seat surface, a dashboard surface, and a console
surface.
19. The method of claim 13, wherein the pattern is backlit.
20. The method of claim 13, wherein the pattern is textured.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims the benefit of U.S.
Provisional Application No. 60/654,312 filed on Feb. 19, 2005, and
claims priority to and is a Continuation-in-Part Application of
U.S. patent application Ser. No. 11/075,837 filed on Mar. 9, 2005,
which claims the benefit of U.S. Provisional Application
60/552,677, filed on Mar. 12, 2004, all of which are incorporated
herein by reference in their entirety.
BACKGROUND
[0002] The present disclosure generally relates to on demand
morphable body moldings and surfaces, and more particularly, to on
demand morphable body moldings and surfaces based on active
materials.
[0003] Current vehicle members such as body side moldings, rub
strips, edge guards and bumpers of various sorts have been employed
for years. These types of vehicle members have both decorative and
protective functions. For example, edge guards protect the edge of
a door, a bumper, or the like and can be made to decoratively
accent the vehicle surface. Body side moldings generally are formed
of numerous pieces horizontally aligned and attached on the side of
a vehicle. Body side moldings must take into account the clearances
associated with the opening and closure of door assemblies in
vehicles. As a result, some vehicles require a portion of the
molding to be cut-away to permit opening and closure of the door.
The problem with having to form the molding in this manner is that
it decreases the aesthetic qualities of the molding. From a
distance, one has difficulty in distinguishing whether the cutaway
portion represents damage to the vehicle or is part of the
design.
[0004] Current vehicle members of the type described above are
generally static. That is, these vehicle members are either present
on the vehicle or not. For example, mounting a license bracket on
the front of the vehicle member is not always needed in the
intended vehicle market. There are many jurisdictions that do not
require front license plates, whereas others do. However, in view
of costs, manufacturers will generally produce all of its vehicle
models with a license bracket. This presents an aesthetic problem
when the jurisdiction does not require a front license plate and/or
an owner does not want a front license plate.
[0005] Accordingly, there is a need in the art for on-demand
morphable body moldings and surfaces that provide a means for
protecting the vehicle and are aesthetically pleasing. It would be
particularly advantageous if the vehicle member can reversibly
morph on demand.
BRIEF SUMMARY
[0006] Disclosed herein are morphable vehicle members and methods
of use. In one embodiment, a non-active material based portion
coupled to an active material based portion, wherein the active
material based portion comprises an active material adapted to
change at least one attribute in response to an activation signal,
wherein the change in the at least one attribute changes a modulus
property, a shape orientation, or a combination of the modulus
property change and the shape orientation change to the active
material base portion; an activation device in operative
communication with the active material adapted to provide the
activation signal; and a controller in operative communication with
the activation device.
[0007] In another embodiment, at least a two part morphable molding
for a vehicle contiguously spanning an interface of a door and a
doorframe, the morphable molding comprising a first molding
attached to the doorframe surface; a second molding attached to the
door comprising an active material based portion contiguous to the
first molding, the active material based portion comprising an
active material adapted to change at least one attribute in
response to an activation signal, wherein the change in the at
least one attribute changes a modulus property, a shape
orientation, or a combination of the modulus property change and
the shape orientation change to the active material base portion to
provide door clearance upon opening the door an activation device
in operative communication with the active material adapted to
provide the activation signal; and a controller in operative
communication with the activation device.
[0008] In one embodiment, a method for selectively forming or
erasing a raised pattern in a vehicle surface comprises forming a
pattern comprising a active material in the vehicle surface,
wherein the active material has a selected one of a trained shape
that projects from a surrounding vehicle surface and a trained
shape that is substantially aligned with a contour of the
surrounding surface; activating the active material, wherein
activating the active material changes the selected one of the
trained shape that projects to the substantially align with the
contour of the surrounding surface and the trained shape that is
substantially aligned to project from the contour of the
surrounding vehicle surface; and deactivating the active
material.
[0009] The above described and other features are exemplified by
the following figures and detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Referring now to the figures, which are exemplary
embodiments and wherein like elements are numbered alike:
[0011] FIG. 1 is a schematic representation of a cross section of a
body side molding prior to activation in accordance with one
embodiment of the disclosure;
[0012] FIG. 2 is the schematic representation of the cross section
of body side molding taken along lines 2-2 of FIG. 1 upon
activation of the at least one active material in accordance with
one embodiment of the disclosure;
[0013] FIG. 3 is a schematic representation of a cross section of
springs in a morphable vehicle member prior to activation in
accordance with one embodiment of the disclosure;
[0014] FIG. 4 is a schematic representation of a cross section of a
morphable vehicle member prior to activation in accordance with one
embodiment of the disclosure;
[0015] FIG. 5 is the schematic representation of the cross section
of the morphable vehicle member in FIG. 5 upon activation of the at
least one active material in accordance with one embodiment of the
disclosure;
[0016] FIG. 6 is a schematic representation of a cross section of a
morphable vehicle member prior to activation in accordance with one
embodiment of the disclosure; and
[0017] FIG. 7 is the schematic representation of the cross section
of the morphable vehicle member in FIG. 7 upon activation of the at
least one active material in accordance with one embodiment of the
disclosure.
DETAILED DESCRIPTION
[0018] The present disclosure generally relates to morphable
vehicle members and methods of use in a vehicle, and in particular,
to morphable vehicle members comprising an active material that
changes the shape orientation and/or modulus properties of the
vehicle member in response to an activation signal. Upon
deactivation, the morphable vehicle member can recover its original
configuration. In some embodiments, the active materials can be
employed as actuators disposed within the morphable vehicle member
to effect the change in shape orientation and/or modulus
properties. Although reference will made herein to automotive
applications, it is contemplated that the morphable vehicle members
can be adapted to form various surfaces, wherein on demand
morphable surfaces are desired such as may be desired for
airplanes, trains, buses, trucks, vans, recreational vehicles and
the like.
[0019] As used herein, the term "vehicle member" refers to various
parts that form the vehicle, which include, but are not intended to
be limited to, body side moldings, rub strips, edge guards,
bumpers, fenders, front end structures, license plate brackets,
trunk panels, hood panels, body panels, door panels, and the like.
It also refers to interior surfaces of the vehicle which include,
but are not limited to, the dashboard, the sun visor, the center
console, the armrest, the seat, the headrest, the door surface, and
the like. Other suitable parts or components of the vehicle will be
apparent to those skilled in the art in view of this
disclosure.
[0020] The morphable vehicle member generally comprises an active
material adapted to change shape orientation in response to an
activation signal. The term "active material" as used herein refers
to several different classes of materials all of which exhibit a
change in at least one attribute such as dimension, shape, and/or
flexural modulus when subjected to at least one of many different
types of applied activation signals, examples of such signals being
thermal, electrical, magnetic, mechanical, pneumatic, and the like.
One class of active materials is shape memory materials. These
materials exhibit a shape memory effect. Specifically, after being
deformed pseudoplastically, they can be restored to their original
shape in response to the activation signal. Suitable shape memory
materials include, without limitation, shape memory alloys (SMA),
ferromagnetic SMAs, and shape memory polymers (SMP). A second class
of active materials can be considered as those that exhibit a
change in at least one attribute when subjected to an applied
activation signal but revert back to their original state upon
removal of the applied activation signal. Active materials in this
category include, but are not limited to, piezoelectric materials,
electroactive polymers (EAP), magnetorheological fluids and
elastomers (MR), electrorheological fluids (ER), electrostrictive
polymers, ionic polymer gels, composites of one or more of the
foregoing materials with non-active materials, combinations
comprising at least one of the foregoing materials, and the like.
The active material may be integrated within a member of the
vehicle or may define the complete member. Moreover, selective
morphing can be effected by means of flexural modulus changes,
shape changes, rotations, reorientation, and the like. Of the above
noted materials, SMA- and SMP-based vehicle member assemblies may
further include a return mechanism in some embodiments to restore
the original geometry of the assembly. The return mechanism can be
mechanical, pneumatic, hydraulic, or based on one of the
aforementioned active materials.
[0021] By utilizing the active material, the morphable vehicle
member can reversibly change at least one attribute to provide
protection on demand, provide enhanced appearance of the vehicle
member, as well as provide `disappearing` mounts, where desired and
configured. In addition, the active material can be configured to
function as an actuator to effect the change in shape orientation
and/or modulus properties, i.e., effect morphing. Applying an
activation signal to the active material can effect the reversible
change on demand. Suitable activation signals will depend on the
particular active material used. As previously discussed, the
activation signal provided for changing the shape orientation of
the vehicle member may include a mechanical loading or stressing, a
thermal signal, an electrical signal, a magnetic signal and
combinations comprising at least one of the foregoing signals, and
the like.
[0022] Referring now to FIGS. 1-2, there is shown an exemplary
morphable vehicle member 10 suitable for use as body side molding
spanning an interface 12 between a body surface 13 and a door
surface 16. The vehicle member 10 has an active material portion
18, which is shown attached to a conventional body side molding
portion 20 of the door surface 16. The body side molding 16 spans
across the interface 12 and is linearly aligned with a molding
portion 14 disposed on the body surface 13. As shown more clearly
in FIG. 2, the active material portion 18 generally includes a
rigid base 22 and a flexible covering 24 attached thereto with
respect to the base 22. The vehicle member 10 including the active
material portion 18 can be fastened to a body surface of a vehicle
(e.g., door surface 16) by fasteners or adhesives such as
double-sided adhesive tape, acrylic foam tape, and the like. The
active material portion 18 comprises an active material 26 adapted
to change a shape orientation and/or modulus properties in response
to an activation signal. The active material can take many forms as
previously discussed. For example, the active material can be in
the form of a solid body of shape memory polymer such that
activation causes a modulus change. In other examples, the active
material can take the form of shape memory alloy springs
intermediate the flexible covering. Still further, the space
intermediate the flexible covering and base can be filled with an
electrorheological or magnetorheological fluid. Other variations
are contemplated and well within the skill of those in the art.
[0023] The active material 26 is in operative communication with an
activation device 28 and a controller 30. The activation device 28
provides the appropriate activation signal to the active material
26 based on signals provided by the controller 30. By way of
example, the vehicle member 10 may form a body side molding that
provides a substantially continuous surface across interfaces such
as those provided by interface 12. Upon selective activation of the
active material portion 18, e.g., a shape memory polymer, the shape
orientation and/or modulus properties of the active material
portion 18 change so as to provide the desired amount of clearance
between the door surface 16 and door frame surface 14 to permit
door opening (as shown by the dotted line structure 32 in FIG. 2).
Although the vehicle member 10 is illustrated as having a hollow
interior region defined by the flexible covering 12 and the rigid
base 14, it is contemplated that the flexible covering 12 and rigid
base could form a solid structure, i.e., no hollow interior region.
Moreover, the entire vehicle member 10 (e.g., body molding) can be
formed of the active material or selected portions thereof as
shown.
[0024] Optionally, the active material can passively morph the
vehicle member 10 without an applied activation signal from the
controller. For example, the active material 26 can be selected to
be undergo a change in shape orientation and modulus properties
upon a mechanical stress, e.g., a pressure loading, such as may be
caused by opening the door to allow one to enter and to exit. This,
for example, is the case for SMA when in its austenitic phase,
i.e., an example of superelasticity. Upon opening the door, a
portion of the vehicle member 10 contacts the active material
portion 18 causing it to plastically deform. When the door is not
opened, the active material 26 is unloaded and thus deactivated and
the shape and modulus properties of the vehicle member 10 revert to
its original shape and modulus properties in the absence of the
load, which can be used to provide the continuous surface across
various interfaces such as the door and doorframe so as to maintain
a pleasing aesthetic appearance to the vehicle.
[0025] As another example, the morphable vehicle member can be
configured for use as a rub strip formed of the active material,
e.g., a shape memory polymer. An activation signal in response to
the anticipation of a door opening, such as movement of door
handle, pressing of remote key fob and the like can be used to
trigger thermal activation of the shape memory polymer to effect a
change in its modulus allowing deformation to occur in the rub
strip upon door opening. The shape memory polymer would remain
heated until the door was closed or be reheated upon door closing.
The heated shape memory polymer rub strip after the door is closed
is no longer under a load and would revert back to its original
configuration. In this manner, opening and closing of the door can
be programmed with minimal effort or resistance as contributed by
forces associated with the rub strip.
[0026] Referring now to FIG. 3, there is shown a cross sectional
view of morphable vehicle member 40. The vehicle member 40
comprises the rigid base 22 and flexible covering 24 that
cooperatively define a hollow interior region 42. A plurality of
wires 44 is disposed within the interior region 42 having one end
attached to the rigid base 22 and the other end attached to an
underside of the flexible covering 24. The wires 44 can take any
form including but not limited to strips, bands, springs, and the
like. The plurality of wires 44 is formed of the active material
and is in operative communication with the activation device 28 and
controller 30, which provides the activation signal to the active
material. Activation of the active material effects a change in
shape orientation and/or modulus properties such that the shape
changes to the dotted line structure 46 as shown or elastic
compression can occur upon application of a load, e.g., contact of
the active material portion with a door frame surface.
[0027] By way of example, the wires 44 can be formed of a shape
memory alloy. Applying an activation signal to the shape memory
alloy wires 44 cause the shape memory alloy to contract to the
second shape orientation as evidenced by the dotted line structure.
The location of the shape memory alloy wires 44 can vary depending
on intended amount of morphing within the vehicle member 40 as well
as the desired application, all of which is well within the skill
of those in the art in view of this disclosure
[0028] As previously described, the controller 30 can be programmed
to deliver the activation signal upon an event such as a door
opening and discontinuing the activation signal upon door closing.
Alternatively, the activation signal may be initiated by electronic
key fob, pressing or activating the power unlock buttons indicating
one is entering or exiting the vehicle, and the like. Upon
receiving the activation signal, the shape memory alloy wires 44
contract causing the flexible covering 24 to flex inward.
[0029] In another embodiment, the active material wires can be
utilized to expand causing desired displacement as would be
apparent to those skilled in the art in view of this disclosure.
Moreover, the desired displacement can also be obtained with the
use of other active materials such as electroactive polymers,
piezoelectric elastomers, active material fluids that selectively
expand or contract, and the like.
[0030] Aside from strict shape recovery, any active material that
can be made to linearly expand or contract may be used to produce a
bending actuator by combining the active material with a non-active
elastic member. In the literature, this is generally referred to as
a unimorph actuator. If both components are made of the same
material but made to deform in opposite directions, the material
becomes a bimorph. For on demand applications such as those
described above, some active materials may be appropriate
themselves for the outer surface of the morphable vehicle
member.
[0031] Using an active material that expands or contracts can
induce bending to the left or right. In the bimorph configuration,
either direction can also be achieved depending on orientation of
the active material layers. An unimorph may be created by using a
shape memory alloy, conducting polymer, electrostrictive polymer,
or other axially straining material, along with an elastic
component that causes a bending couple to be created. The elastic
member can belong to many material classes including metallic
alloys, polymers, and ceramics. Preferred materials are those which
exhibit large elastic strain limits, and those which can
efficiently store mechanical energy. Secondary considerations
include those which may be easily bonded to the at least one active
material, have properties that are acceptable in the working
temperature range, and have adequate toughness to survive repeated
actuation. A bimorph may be created for any material in which the
material may be driven into both extension and compression
depending on the driving signal. Piezoelectric materials can be
used for this effect. Ionic polymer actuators such as ionic polymer
metal composites and conducting polymers intrinsically exhibit this
effect due to the transport of ionic species that cause swelling
across a membrane. Therefore, these materials are preferably used
for this type of deformation.
[0032] Referring now to FIGS. 4 and 5, there is shown an exemplary
morphable vehicle member 50 configured for use as an edge guard.
Edge guards are generally employed to protect the vehicle from
dents, dings and scratches when doors are opened and bumped against
neighboring vehicles. For example, the edge guard 50 may be
configured to protect the vehicle door, trunk door, bumper, and the
like during normal operation of the vehicle.
[0033] The vehicle member 50 in accordance with embodiment
comprises localized regions 52 of active material in operative
communication with regions 54 of a non-active material 54. In FIG.
4, the vehicle member 50 is shown in an initial substantially
straight configuration. FIG. 5 illustrates the vehicle member 50 in
a second shape orientation in the activated state, wherein the edge
guard assumes a curvilinear shape. In this manner, the edge guard
can be selectively activated to assume the curvilinear shape so as
to protect the other vehicle surfaces from being contacted. When
deactivated, the edge guard is restored to its original shape,
which in some applications can be coplanar with the surrounding
surface contour.
[0034] In operation, applying an activation signal to the regions
52 causes the active material to deform to the second shape
orientation. The deformation causes the active material to buckle
along a predefined path absorbing kinetic energy associated with
any minor impact event. In the event the non-active material is
fixedly attached to a surface, the localized region 52 would bow
out or in depending on the intended application. As such, the
location of the active material will vary depending on the
dimensional axes and the desired application. In this manner,
impact of an object can cause the vehicle member 10 to buckle along
the predefined path. For example, the edge guard can be
strategically positioned on the vehicle to provide protection
against a shopping cart impact.
[0035] Alternatively, the morphable vehicle member 50 is formed
entirely of the active material, which changes at least one
attribute upon an activation signal. The morphable vehicle member
may be in an initial straight configuration and bend into a curved
position upon activation signal. For example, the door edge guard
wraps around the edge of the door protecting it on demand. The
amount of curvature would depend on the intended application.
[0036] In other embodiments, the morphable rub strips can be
configured to provide active damping by expanding outward in
response to the activation signal. For example, dielectric
elastomers can be used as the morphable rub strip. For example, a
sealed tube of the dielectric elastomer is fabricated with a
defined internal pressure and applied to the desired locations at
about the vehicle edge. As voltage is applied, the tube expands in
diameter in an amount effective to provide effective protection
against dings. In another example, rub strips are formed of shape
memory polymer, which can be heated and thus softened upon door
opening to minimize any impact damage upon striking a neighboring
object such as side of a vehicle. After closing of the door, the
shape memory polymer can return to its original undeformed geometry
and upon discontinuation of activation, the shape memory polymer
can stiffen upon cooling.
[0037] Referring now to FIGS. 6 and 7, there is shown a vehicle
bumper 60 employing a morphable vehicle member 62 to define a
license plate bracket. Vehicle member 62 is defined by a pattern
formed of the active material. Alternatively, the entire front
bumper may be formed of the active material with portions
corresponding to the license bracket selectively activated,
although this is generally less preferred in view of the material
and processing costs associated with the active materials.
[0038] As shown more clearly in FIG. 7, applying an activation
signal to the active material in the bumper causes the license
plate bracket to appear or disappear depending on the configuration
of and type of active material used. For example, in the case of
shape memory polymers, a thermal activation signal can be applied
or a load can be applied to plastically deform a preformed license
bracket portion (i.e., the preformed license bracket includes
projections emanating from the major planar surfaces that generally
define the bumper) and make it uniformly aligned with the remaining
contour surface of the front bumper. Subsequently cooling the
license bracket portion will lock the plastic deformation in place
and cause the "disappearance" of the bracket. If the surface
contour associated with the license plate bracket is desired, then
reheating the license bracket region in the absence of a load will
return the license bracket portion to its original shape
orientation. Depending on the type of active material utilized, the
molding formed of the active material can be made to appear or
disappear upon activation.
[0039] In another embodiment, regions of SMP can be located in
various exterior and interior surfaces of the vehicle. A thermal
activation through the use of heated tools shaped in a pattern that
is desired can be used to create personalized and/or distinctive
bas-relief engravings and displays. If one no longer desires these
engravings and displays, heating the shape memory polymer surface
with surface loads removed will "erase" them. Suitable interior and
exterior surfaces include, but are not limited to, a vehicle
bumper, an interior surface, a steering wheel surface, a seat
surface, a dashboard surface, a console surface, and the like.
[0040] In another embodiment, localized regions of shape memory
polymer can be located in exterior regions of the vehicle that are
subject to dings, dents and scratches. To remove these plastic
deformations, one would apply thermal activation in the absence of
a load to heal and/or repair the surface regions made of shape
memory polymer. Of course, the repair would be limited to damage
associated with plastic deformation of the surface as opposed to
abrasions, tears, avulsions, breaks and the like.
[0041] Optionally, the pattern of the active material has a
thickness and/or is semi-opaque or translucent such that the
pattern can be backlit. For example, a lighting panel can be
disposed behind the pattern to provide the backlight.
Alternatively, a reflective or bright panel can be employed, e.g.,
a chrome panel. In this manner, the pattern can be readily visible
and aesthetically interesting. Still further, the pattern can be
textured.
[0042] In other examples, the morphable vehicle member is a trunk,
a hood, a spoiler, a dashboard, a sun visor, a center console, an
armrest, seat, headrest and the like. The morphable vehicle member
has localized regions of the at least one active material. For
example, the dashboard is formed of a shape memory polymer material
which can be used to create personalized/distinctive bas-relief
engravings and displays with heated tools. Subsequently, if one
desires to remove the engravings and/or displays, the localized
regions of SMP can be reheated with surface loads removed, thus
"erasing" the displays and/or engravings.
[0043] In another example, the morphable vehicle member is a front
spoiler, fender, bumper and the like. These areas typically receive
nicks, dents, scratches or damage at low speeds due to its location
close to the ground. For example, the front spoiler on a sports
vehicle has at least one active material. The driver can
plastically deform the front spoiler with rocks. Upon reheating the
at least one active material in the front spoiler with surface
loads removed, the plastic deformation can be repaired in the front
spoiler. Alternatively, this can be applied for fenders, bumpers
and the like.
[0044] Desirably, the change in at least one attribute of the
active material remains for the duration of the applied activation
signal. Also desirably, upon discontinuation of the activation
signal, the change in the at least one attribute reverts
substantially to its original form prior to the activation. In this
manner, reversibility can advantageously occur.
[0045] Shape memory polymers (SMPs) generally refer to a group of
polymeric materials that demonstrate the ability to return to some
previously defined shape when subjected to an appropriate thermal
stimulus. Shape memory polymers may be thermoresponsive (i.e., the
change in the property is caused by a thermal activation signal),
photoresponsive (i.e., the change in the property is caused by a
light-based activation signal), moisture-responsive (i.e., the
change in the property is caused by a liquid activation signal such
as humidity, water vapor, or water), or a combination comprising at
least one of the foregoing.
[0046] Generally, SMPs are phase segregated co-polymers comprising
at least two different units, which may be described as defining
different segments within the SMP, each segment contributing
differently to the overall properties of the SMP. As used herein,
the term "segment" refers to a block, graft, or sequence of the
same or similar monomer or oligomer units, which are copolymerized
to form the SMP. Each segment may be crystalline or amorphous and
will have a corresponding melting point or glass transition
temperature (Tg), respectively. The term "thermal transition
temperature" is used herein for convenience to generically refer to
either a Tg or a melting point depending on whether the segment is
an amorphous segment or a crystalline segment. For SMPs comprising
(n) segments, the SMP is said to have a hard segment and (n-1) soft
segments, wherein the hard segment has a higher thermal transition
temperature than any soft segment. Thus, the SMP has (n) thermal
transition temperatures. The thermal transition temperature of the
hard segment is termed the "last transition temperature", and the
lowest thermal transition temperature of the so-called "softest"
segment is termed the "first transition temperature". It is
important to note that if the SMP has multiple segments
characterized by the same thermal transition temperature, which is
also the last transition temperature, then the SMP is said to have
multiple hard segments.
[0047] When the SMP is heated above the last transition
temperature, the SMP material can be imparted a permanent shape. A
permanent shape for the SMP can be set or memorized by subsequently
cooling the SMP below that temperature. As used herein, the terms
"original shape", "previously defined shape", and "permanent shape"
are synonymous and are intended to be used interchangeably. A
temporary shape can be set by heating the material to a temperature
higher than a thermal transition temperature of any soft segment
yet below the last transition temperature, applying an external
stress or load to deform the SMP, and then cooling below the
particular thermal transition temperature of the soft segment while
maintaining the deforming external stress or load.
[0048] The permanent shape can be recovered by heating the
material, with the stress or load removed, above the particular
thermal transition temperature of the soft segment yet below the
last transition temperature. Thus, it should be clear that by
combining multiple soft segments it is possible to demonstrate
multiple temporary shapes and with multiple hard segments it may be
possible to demonstrate multiple permanent shapes. Similarly using
a layered or composite approach, a combination of multiple SMPs
will demonstrate transitions between multiple temporary and
permanent shapes.
[0049] For SMPs with only two segments, the temporary shape of the
shape memory polymer is set at the first transition temperature,
followed by cooling of the SMP, while under load, to lock in the
temporary shape. The temporary shape is maintained as long as the
SMP remains below the first transition temperature. The permanent
shape is regained when the SMP is once again brought above the
first transition temperature with the load removed. Repeating the
heating, shaping, and cooling steps can repeatedly reset the
temporary shape.
[0050] Most SMPs exhibit a "one-way" effect, wherein the SMP
exhibits one permanent shape. Upon heating the shape memory polymer
above a soft segment thermal transition temperature without a
stress or load, the permanent shape is achieved and the shape will
not revert back to the temporary shape without the use of outside
forces.
[0051] As an alternative, some shape memory polymer compositions
can be prepared to exhibit a "two-way" effect, wherein the SMP
exhibits two permanent shapes. These systems include at least two
polymer components. For example, one component could be a first
cross-linked polymer while the other component is a different
cross-linked polymer. The components are combined by layer
techniques, or are interpenetrating networks, wherein the two
polymer components are cross-linked but not to each other. By
changing the temperature, the shape memory polymer changes its
shape in the direction of a first permanent shape or a second
permanent shape. Each of the permanent shapes belongs to one
component of the SMP. The temperature dependence of the overall
shape is caused by the fact that the mechanical properties of one
component ("component A") are almost independent of the temperature
in the temperature interval of interest. The mechanical properties
of the other component ("component B") are temperature dependent in
the temperature interval of interest. In one embodiment, component
B becomes stronger at low temperatures compared to component A,
while component A is stronger at high temperatures and determines
the actual shape. A two-way memory device can be prepared by
setting the permanent shape of component A ("first permanent
shape"), deforming the device into the permanent shape of component
B ("second permanent shape"), and fixing the permanent shape of
component B while applying a stress.
[0052] It should be recognized by one of ordinary skill in the art
that it is possible to configure SMPs in many different forms and
shapes. Engineering the composition and structure of the polymer
itself can allow for the choice of a particular temperature for a
desired application. For example, depending on the particular
application, the last transition temperature may be about 0.degree.
C. to about 300.degree. C. or above. A temperature for shape
recovery (i.e., a soft segment thermal transition temperature) may
be greater than or equal to about -30.degree. C. Another
temperature for shape recovery may be greater than or equal to
about 40.degree. C. Another temperature for shape recovery may be
greater than or equal to about 100.degree. C. Another temperature
for shape recovery may be less than or equal to about 250.degree.
C. Yet another temperature for shape recovery may be less than or
equal to about 200.degree. C. Finally, another temperature for
shape recovery may be less than or equal to about 150.degree.
C.
[0053] Optionally, the SMP can be selected to provide
stress-induced yielding, which may be used directly (i.e. without
heating the SMP above its thermal transition temperature to
`soften` it) to make the panel conform to a given surface as may be
desired for different applications. The maximum strain that the SNP
can withstand in this case can, in some embodiments, be comparable
to the case when the SMP is deformed above its thermal transition
temperature.
[0054] Although reference has been, and will further be, made to
thermoresponsive SMPs, those skilled in the art in view of this
disclosure will recognize that photoresponsive, moisture-responsive
SMPs and SMPs activated by other methods may readily be used in
addition to or substituted in place of thermoresponsive SMPs. For
example, instead of using heat, a temporary shape may be set in a
photoresponsive SMP by irradiating the photoresponsive SMP with
light of a specific wavelength (while under load) effective to form
specific crosslinks and then discontinuing the irradiation while
still under load. To return to the original shape, the
photoresponsive SMP may be irradiated with light of the same or a
different specific wavelength (with the load removed) effective to
cleave the specific crosslinks. Similarly, a temporary shape can be
set in a moisture-responsive SMP by exposing specific functional
groups or moieties to moisture (e.g., humidity, water, water vapor,
or the like) effective to absorb a specific amount of moisture,
applying a load or stress to the moisture-responsive SMP, and then
removing the specific amount of moisture while still under load. To
return to the original shape, the moisture-responsive SMP may be
exposed to moisture (with the load removed).
[0055] Suitable shape memory polymers, regardless of the particular
type of SMP, can be thermoplastics, thermosets-thermoplastic
copolymers, interpenetrating networks, semi-interpenetrating
networks, or mixed networks. The SMP "units" or "segments" can be a
single polymer or a blend of polymers. The polymers can be linear
or branched elastomers with side chains or dendritic structural
elements. Suitable polymer components to form a shape memory
polymer include, but are not limited to, polyphosphazenes,
poly(vinyl alcohols), polyamides, polyimides, polyester amides,
poly(amino acid)s, polyanhydrides, polycarbonates, polyacrylates,
polyalkylenes, polyacrylamides, polyalkylene glycols, polyalkylene
oxides, polyalkylene terephthalates, polyortho esters, polyvinyl
ethers, polyvinyl esters, polyvinyl halides, polyesters,
polylactides, polyglycolides, polysiloxanes, polyurethanes,
polyethers, polyether amides, polyether esters, and copolymers
thereof. Examples of suitable polyacrylates include poly(methyl
methacrylate), poly(ethyl methacrylate), poly(butyl methacrylate),
poly(isobutyl methacrylate), poly(hexyl methacrylate),
poly(isodecyl methacrylate), poly(lauryl methacrylate), poly(phenyl
methacrylate), poly(methyl acrylate), poly(isopropyl acrylate),
poly(isobutyl acrylate) and poly(octadecylacrylate). Examples of
other suitable polymers include polystyrene, polypropylene,
polyvinyl phenol, polyvinylpyrrolidone, chlorinated polybutylene,
poly(octadecyl vinyl ether), poly (ethylene vinyl acetate),
polyethylene, poly(ethylene oxide)-poly(ethylene terephthalate),
polyethylene/nylon (graft copolymer), polycaprolactones-polyamide
(block copolymer), poly(caprolactone) diniethacrylate-n-butyl
acrylate, poly(norbornyl-polyhedral oligomeric silsequioxane),
polyvinylchloride, urethane/butadiene copolymers,
polyurethane-containing block copolymers, styrene-butadiene block
copolymers, and the like. The polymer(s) used to form the various
segments in the SMPs described above are either commercially
available or can be synthesized using routine chemistry. Those of
skill in the art can readily prepare the polymers using known
chemistry and processing techniques without undue
experimentation.
[0056] As will be appreciated by those skilled in the art,
conducting polymerization of different segments using a blowing
agent can form a shape memory polymer foam, for example, as may be
desired for some applications. The blowing agent can be of the
decomposition type (evolves a gas upon chemical decomposition) or
an evaporation type (which vaporizes without chemical reaction).
Exemplary blowing agents of the decomposition type include, but are
not intended to be limited to, sodium bicarbonate, azide compounds,
ammonium carbonate, ammonium nitrite, light metals which evolve
hydrogen upon reaction with water, azodicarbonamide, N,N'
dinitrosopentamethylenetetramine, and the like. Exemplary blowing
agents of the evaporation type include, but are not intended to be
limited to, trichloromonofluoromethane, trichlorotrifluoroethane,
methylene chloride, compressed nitrogen, and the like.
[0057] Shape memory alloys are alloy compositions with at least two
different temperature-dependent phases. The most commonly utilized
of these phases are the so-called martensite and austenite phases.
In the following discussion, the martensite phase generally refers
to the more deformable, lower temperature phase whereas the
austenite phase generally refers to the more rigid, higher
temperature phase. When the shape memory alloy is in the martensite
phase and is heated, it begins to change into the austenite phase.
The temperature at which this phenomenon starts is often referred
to as austenite start temperature (A.sub.s). The temperature at
which this phenomenon is complete is called the austenite finish
temperature (A.sub.f). When the shape memory alloy is in the
austenite phase and is cooled, it begins to change into the
martensite phase, and the temperature at which this phenomenon
starts is referred to as the martensite start temperature
(M.sub.s). The temperature at which austenite finishes transforming
to martensite is called the martensite finish temperature
(M.sub.f). It should be noted that the above-mentioned transition
temperatures are functions of the stress experienced by the SMA
sample. Specifically, these temperatures increase with increasing
stress. In view of the foregoing properties, deformation of the
shape memory alloy is preferably at or below the austenite
transition temperature (at or below A.sub.s). Subsequent heating
above the austenite transition temperature causes the deformed
shape memory material sample to revert back to its permanent shape.
Thus, a suitable activation signal for use with shape memory alloys
is a thermal activation signal having a magnitude that is
sufficient to cause transformations between the martensite and
austenite phases.
[0058] The temperature at which the shape memory alloy remembers
its high temperature form when heated can be adjusted by slight
changes in the composition of the alloy and through
thermo-mechanical processing. In nickel-titanium shape memory
alloys, for example, it can be changed from above about 100.degree.
C. to below about -100.degree. C. The shape recovery process can
occur over a range of just a few degrees or exhibit a more gradual
recovery. The start or finish of the transformation can be
controlled to within a degree or two depending on the desired
application and alloy composition. The mechanical properties of the
shape memory alloy vary greatly over the temperature range spanning
their transformation, typically providing shape memory effect,
superelastic effect, and high damping capacity. For example, in the
martensite phase a lower elastic modulus than in the austenite
phase is observed. Shape memory alloys in the martensite phase can
undergo large deformations by realigning the crystal structure
arrangement with the applied stress. As will be described in
greater detail below, the material will retain this shape after the
stress is removed.
[0059] Suitable shape memory alloy materials for use in the panel
include, but are not intended to be limited to, nickel-titanium
based alloys, indium-titanium based alloys, nickel-aluminum based
alloys, nickel-gallium based alloys, copper based alloys (e.g.,
copper--zinc alloys, copper-aluminum alloys, copper-gold, and
copper-tin alloys), gold-cadmium based alloys, silver-cadmium based
alloys, indium-cadmium based alloys, manganese-copper based alloys,
iron-platinum based alloys, iron-palladium based alloys, and the
like. The alloys can be binary, ternary, or any higher order so
long as the alloy composition exhibits a shape memory effect, e.g.,
change in shape, orientation, yield strength, flexural modulus,
damping capacity, superelasticity, and/or similar properties.
Selection of a suitable shape memory alloy composition depends on
the temperature range where the component will operate.
[0060] Aside from strict shape recovery, any active material that
can be made to linearly expand or contract may be used to produce a
bending actuator by combining this active material with a
non-active elastic member. In the literature, this is generally
referred to as a unimorph actuator. If both components are made of
the same material but made to deform in opposite directions, the
material becomes a bimorph. For on demand applications, some
materials may be appropriate themselves for the outer surface of
the vehicle control mechanism.
[0061] Using the at least one active material that expands or
contracts can induce bending to the left or right, respectively. In
the bimorph either direction can also be achieved depending on
orientation of the at least one active material layers. An unimorph
may be created by using a shape memory alloy, conducting polymer,
electrostrictive polymer, or other axially straining material,
along with an elastic component that causes bending couple to be
created. The elastic member can belong to many material classes
including metallic alloys, polymers, and ceramics. Preferred
materials are those which exhibit large elastic strain limits, and
those which can efficiently store mechanical energy. Secondary
considerations include those which may be easily bonded to the at
least one active material, have properties that are acceptable in
the working temperature range, and have adequate toughness to
survive repeated actuation. A bimorph may be created for any
material in which the material may be driven into both extension
and compression depending on the driving signal. Ionic polymer
actuators such as IPMC and conducting polymers intrinsically
exhibit this effect due to the transport of ionic species that
cause swelling across a membrane. Therefore, these materials are
preferably used for this type of deformation.
[0062] Electroactive polymers include those polymeric materials
that exhibit piezoelectric, pyroelectric, or electrostrictive
properties in response to electrical or mechanical fields. An
example of an electrostrictive-grafted elastomer with a
piezoelectric poly(vinylidene fluoride-trifluoro-ethylene)
copolymer. This combination has the ability to produce a varied
amount of ferroelectric-electrostrictive molecular composite
systems.
[0063] Materials suitable for use as an electroactive polymer may
include any substantially insulating polymer or rubber (or
combination thereof) that deforms in response to an electrostatic
force or whose deformation results in a change in electric field.
Exemplary materials suitable for use as a pre-strained polymer
include silicone elastomers, acrylic elastomers, polyurethanes,
thermoplastic elastomers, copolymers comprising PVDF,
pressure-sensitive adhesives, fluoroelastomers, polymers comprising
silicone and acrylic moieties, and the like. Polymers comprising
silicone and acrylic moieties may include copolymers comprising
silicone and acrylic moieties, polymer blends comprising a silicone
elastomer and an acrylic elastomer, for example.
[0064] Materials used as an electroactive polymer may be selected
based on one or more material properties such as a high electrical
breakdown strength, a low modulus of elasticity--(for large or
small deformations), a high dielectric constant, and the like. In
one embodiment, the polymer is selected such that is has an elastic
modulus at most about 100 MPa. In another embodiment, the polymer
is selected such that is has a maximum actuation pressure between
about 0.05 MPa and about 10 MPa, and preferably between about 0.3
MPa and about 3 MPa. In another embodiment, the polymer is selected
such that is has a dielectric constant between about 2 and about
20, and preferably between about 2.5 and about 12. The present
disclosure is not intended to be limited to these ranges. Ideally,
materials with a higher dielectric constant than the ranges given
above would be desirable if the materials had both a high
dielectric constant and a high dielectric strength. In many cases,
electroactive polymers may be fabricated and implemented as thin
films. Thicknesses suitable for these thin films may be below 50
micrometers.
[0065] As electroactive polymers may deflect at high strains,
electrodes attached to the polymers should also deflect without
compromising mechanical or electrical performance. Generally,
electrodes suitable for use may be of any shape and material
provided that they are able to supply a suitable voltage to, or
receive a suitable voltage from, an electroactive polymer. The
voltage may be either constant or varying over time. In one
embodiment, the electrodes adhere to a surface of the polymer.
Electrodes adhering to the polymer are preferably compliant and
conform to the changing shape of the polymer. Correspondingly, the
present disclosure may include compliant electrodes that conform to
the shape of an electroactive polymer to which they are attached.
The electrodes may be only applied to a portion of an electroactive
polymer and define an active area according to their geometry.
Various types of electrodes suitable for use with the present
disclosure include structured electrodes comprising metal traces
and charge distribution layers, textured electrodes comprising
varying out of plane dimensions, conductive greases such as carbon
greases or silver greases, colloidal suspensions, high aspect ratio
conductive materials such as carbon fibrils and carbon nanotubes,
and mixtures of ionically conductive materials.
[0066] Materials used for electrodes of the present disclosure may
vary. Suitable materials used in an electrode may include graphite,
carbon black, colloidal suspensions, thin metals including silver
and gold, silver filled and carbon filled gels and polymers, and
ionically or electronically conductive polymers. It is understood
that certain electrode materials may work well with particular
polymers and may not work as well for others. By way of example,
carbon fibrils work well with acrylic elastomer polymers while not
as well with silicone polymers.
[0067] Suitable piezoelectric materials include, but are not
intended to be limited to, inorganic compounds, organic compounds,
and metals. With regard to organic materials, all of the polymeric
materials with non-centrosymmetric structure and large dipole
moment group(s) on the main chain or on the side-chain, or on both
chains within the molecules, can be used as suitable candidates for
the piezoelectric film. Exemplary polymers include, for example,
but are not limited to, poly(sodium 4-styrenesulfonate), poly
(poly(vinylamine) backbone azo chromophore), and their derivatives;
polyfluorocarbons, including polyvinylidenefluoride, its co-polymer
vinylidene fluoride ("VDF"), co-trifluoroethylene, and their
derivatives; polychlorocarbons, including poly(vinyl chloride),
polyvinylidene chloride, and their derivatives; polyacrylonitriles,
and their derivatives; polycarboxylic acids, including
poly(methacrylic acid), and their derivatives; polyureas, and their
derivatives; polyurethanes, and their derivatives; bio-molecules
such as poly-L-lactic acids and their derivatives, and cell
membrane proteins, as well as phosphate bio-molecules such as
phosphodilipids; polyanilines and their derivatives, and all of the
derivatives of tetramines; polyamides including aromatic polyamides
and polyimides, including Kapton and polyetherimide, and their
derivatives; all of the membrane polymers; poly(N-vinyl
pyrrolidone) (PVP) homopolymer, and its derivatives, and random
PVP-co-vinyl acetate copolymers; and all of the aromatic polymers
with dipole moment groups in the main-chain or side-chains, or in
both the main-chain and the side-chains, and mixtures thereof.
[0068] Piezoelectric material can also comprise metals selected
from the group consisting of lead, antimony, manganese, tantalum,
zirconium, niobium, lanthanum, platinum, palladium, nickel,
tungsten, aluminum, strontium, titanium, barium, calcium, chromium,
silver, iron, silicon, copper, alloys comprising at least one of
the foregoing metals, and oxides comprising at least one of the
foregoing metals. Suitable metal oxides include SiO.sub.2,
Al.sub.2O.sub.3, ZrO.sub.2, TiO.sub.2, SrTiO.sub.3, PbTiO.sub.3,
BaTiO.sub.3, FeO.sub.3, Fe.sub.3O.sub.4, ZnO, and mixtures thereof
and Group VIA and IIB compounds, such as CdSe, CdS, GaAs,
AgCaSe.sub.2, ZnSe, GaP, InP, ZnS, and mixtures thereof.
Preferably, the piezoelectric material is selected from the group
consisting of polyvinylidene fluoride, lead zirconate titanate, and
barium titanate, and mixtures thereof.
[0069] Suitable magnetorheological fluid materials include, but are
not intended to be limited to, ferromagnetic or paramagnetic
particles dispersed in a carrier fluid. Suitable particles include
iron; iron alloys, such as those including aluminum, silicon,
cobalt, nickel, vanadium, molybdenum, chromium, tungsten, manganese
and/or copper; iron oxides, including Fe.sub.2O.sub.3 and
Fe.sub.3O.sub.4; iron nitride; iron carbide; carbonyl iron; nickel
and alloys of nickel; cobalt and alloys of cobalt; chromium
dioxide; stainless steel; silicon steel; and the like. Examples of
suitable particles include straight iron powders, reduced iron
powders, iron oxide powder/straight iron powder mixtures and iron
oxide powder/reduced iron powder mixtures. A preferred
magnetic-responsive particulate is carbonyl iron, more preferably,
reduced carbonyl iron.
[0070] The particle size should be selected so that the particles
exhibit multi-domain characteristics when subjected to a magnetic
field. Diameter sizes for the particles can be less than or equal
to about 1,000 micrometers, with less than or equal to about 500
micrometers preferred, and less than or equal to about 100
micrometers more preferred. Also preferred is a particle diameter
of greater than or equal to about 0.1 micrometer, with greater than
or equal to about 0.5 more preferred, and greater than or equal to
about 10 micrometers especially preferred. The particles are
preferably present in an amount between about 5.0 to about 50
percent by volume of the total MR fluid composition.
[0071] Suitable carrier fluids include organic liquids, especially
non-polar organic liquids. Examples include, but are not limited
to, silicone oils; mineral oils; paraffin oils; silicone
copolymers; white oils; hydraulic oils; transformer oils;
halogenated organic liquids, such as chlorinated hydrocarbons,
halogenated paraffins, perfluorinated polyethers and fluorinated
hydrocarbons; diesters; polyoxyalkylenes; fluorinated silicones;
cyanoalkyl siloxanes; glycols; synthetic hydrocarbon oils,
including both unsaturated and saturated; and combinations
comprising at least one of the foregoing fluids.
[0072] The viscosity of the carrier component can be less than or
equal to about 100,000 centipoise, with less than or equal to about
10,000 centipoise preferred, and less than or equal to about 1,000
centipoise more preferred. Also preferred is a viscosity of greater
than or equal to about 1 centipoise, with greater than or equal to
about 250 centipoise preferred, and greater than or equal to about
500 centipoise especially preferred.
[0073] Aqueous carrier fluids may also be used, especially those
comprising hydrophilic mineral clays such as bentonite or
hectorite. The aqueous carrier fluid may comprise water or water
comprising a small amount of polar, water-miscible organic solvents
such as methanol, ethanol, propanol, dimethyl sulfoxide, dimethyl
formamide, ethylene carbonate, propylene carbonate, acetone,
tetrahydrofuran, diethyl ether, ethylene glycol, propylene glycol,
and the like. The amount of polar organic solvents is less than or
equal to about 5.0% by volume of the total MR fluid, and preferably
less than or equal to about 3.0%. Also, the amount of polar organic
solvents is preferably greater than or equal to about 0.1%, and
more preferably greater than or equal to about 1.0% by volume of
the total MR fluid. The pH of the aqueous carrier fluid is
preferably less than or equal to about 13, and preferably less than
or equal to about 9.0. Also, the pH of the aqueous carrier fluid is
greater than or equal to about 5.0, and preferably greater than or
equal to about 8.0.
[0074] Natural or synthetic bentonite or hectorite may be used. The
amount of bentonite or hectorite in the MR fluid is less than or
equal to about 10 percent by weight of the total MR fluid,
preferably less than or equal to about 8.0 percent by weight, and
more preferably less than or equal to about 6.0 percent by weight.
Preferably, the bentonite or hectorite is present in greater than
or equal to about 0.1 percent by weight, more preferably greater
than or equal to about 1.0 percent by weight, and especially
preferred greater than or equal to about 2.0 percent by weight of
the total MR fluid.
[0075] Optional components in the MR fluid include clays,
organoclays, carboxylate soaps, dispersants, corrosion inhibitors,
lubricants, extreme pressure anti-wear additives, antioxidants,
thixotropic agents and conventional suspension agents. Carboxylate
soaps include ferrous oleate, ferrous naphthenate, ferrous
stearate, aluminum di- and tri-stearate, lithium stearate, calcium
stearate, zinc stearate and sodium stearate, and surfactants such
as sulfonates, phosphate esters, stearic acid, glycerol monooleate,
sorbitan sesquioleate, laurates, fatty acids, fatty alcohols,
fluoroaliphatic polymeric esters, and titanate, aluminate and
zirconate coupling agents and the like. Polyalkylene diols, such as
polyethylene glycol, and partially esterified polyols can also be
included.
[0076] Suitable M elastomer materials include, but are not intended
to be limited to, an elastic polymer matrix comprising a suspension
of ferromagnetic or paramagnetic particles, wherein the particles
are described above. Suitable polymer matrices include, but are not
limited to, poly-alpha-olefins, natural rubber, silicone,
polybutadiene, polyethylene, polyisoprene, and the like.
[0077] The various examples provided herein are merely exemplary
and are not intended to be limiting. Other examples may include
morphable vehicle members such as car seat, door panel, back
spoiler, hood, mudguards, and the like. The morphable vehicle
member advantageously provides protection, repair and
engraving/display options on a vehicle.
[0078] While the disclosure has been described with reference to an
exemplary embodiment, it will be understood by those skilled in the
art that various changes may be made and equivalents may be
substituted for elements thereof without departing from the scope
of the disclosure. In addition, many modifications may be made to
adapt a particular situation or material to the teachings of the
disclosure without departing from the essential scope thereof.
Therefore, it is intended that the disclosure not be limited to the
particular embodiment disclosed as the best mode contemplated for
carrying out this disclosure, but that the disclosure will include
all embodiments falling within the scope of the appended
claims.
* * * * *